Despite the potential for antiretroviral therapy to improve maternal health and reduce mother-to-child transmission of HIV to as low as 1%, HIV-related maternal deaths and HIV infection among infants remain unacceptably high across sub-Saharan Africa. This is particularly true in Kenya, where crucial drop-offs occur in the cascade of prevention of mother-to-child transmission (PMTCT) services. Weak health systems contribute to insufficient service coverage, but many barriers lie beyond the clinic?in the partner, family, and community factors that shape women's health decisions. Our team's research in a high HIV prevalence area of southwestern Kenya has shown that many women avoid couples HIV testing and do not adhere to PMTCT regimens because they fear negative consequences from a male partner. Men can play a crucial supportive role for family health, but male partners in Kenya are poorly engaged in antenatal care and uptake of couples HIV testing during pregnancy is low. Pregnant women desire to be tested for HIV together with their partner and need the support for mutual disclosure involved in couples HIV testing and counseling (CHTC), regardless of whether they know their own HIV status. In this context, we propose to test the efficacy of an interdependence theory-based couples intervention that reaches pregnant women and male partners through home visits by male-female pairs of lay health workers, and includes offer of home-based CHTC services. Our randomized pilot study of this intervention with 96 pregnant couples (R34MH102103) demonstrated significant increases in uptake of couples testing (64% in intervention vs. 23% in control, p<0.001) and significant improvements in health behaviors such as exclusive breastfeeding and postpartum care. We now propose a more robust investigation to determine whether this intervention improves uptake of couples HIV testing and health outcomes over and above less intensive male engagement strategies being used in the region. We propose to conduct a three-arm trial among 1080 pregnant women and partners, randomizing them to home- based couple visits, HIV self-test (HIVST) kits to use with their male partner, or standard care (male partner clinic invitation letters), following couples up to 18 months postpartum. In Aim 1, we will determine the effects of the intervention on our primary outcome of couple HIV testing, compared to HIVST kits and standard care. In Aim 2, we examine intervention impact on HIV prevention behaviors, facility delivery, and postnatal healthcare utilization. Among couples living with HIV, secondary outcomes include maternal VL suppression and HIV-free child survival up to 18 months. In Aim 3, we compare the cost-effectiveness of the home-based couples intervention to the less resource-intensive strategies used in the other two study arms. Our theory- based couples intervention has strong potential to increase couple HIV testing and collaboration for family health. This study will inform decision-makers about cost-effective strategies to engage pregnant couples in PMTCT and family health, with important downstream benefits for maternal, paternal, and infant health.